The present invention relates to liquid inks. More particularly, it relates to liquid inks for marking instruments.
Marking instruments, e.g., pens and markers, have a tip to which a liquid ink is supplied from a reservoir to be applied onto a substrate, such as a sheet of paper, by means of the tip which is moved over the surface of the substrate to leave a liquid trace.
Traditionally, liquid inks for marking instruments either have a viscosity of about 5 centipoise ("cps") or lower (e.g., for fiber tip pens or fountain pens), or have a viscosity of about 7,500 cps or higher (e.g., for ball point pens). The latter usually contain a certain amount of a polymeric material(s).